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Distributed Lock
Redlock controversy, fencing tokens, lease vs lock.SavedSaved on this device — Saved on this device
01Clarifications
What would you ask before drawing a single box?
Ambiguity you would resolve with the interviewer: scope, scale, who uses it, what counts as done.
AI staff engineer
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About Distributed Lock
Redlock controversy, fencing tokens, lease vs lock.
- Difficulty
- advanced
- Time
- about 50 minutes
- Stages
- 10
- Topic
- Consensus, Coordination & Durable Execution
How this problem is worked
Ten stages, from the questions you would ask an interviewer to the trade-offs you would defend. Each asks one question, and the simulator runs the architecture you draw against the requirements you wrote.
- 01ClarificationsWhat would you ask before drawing a single box?
- 02Functional reqsWhat must this system actually do?
- 03Non-functionalWhat must it promise about speed, uptime and correctness?
- 04Capacity estimationHow much load and data does this have to hold?
- 05API designWhat does the outside world call, and what comes back?
- 06Data modelWhat gets stored, and what is it looked up by?
- 07Use-case breakdownHow does each requirement actually get served?
- 08High-level designWhich components handle a request, and in what order?
- 09Deep divesWhich part breaks first, and what do you do about it?
- 10Trade-offsWhat did this design cost, and what breaks at 10×?
Primary sources for this problem
- Kleppmann: How to do distributed locking
- antirez response
More in Consensus, Coordination & Durable Execution
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- Build Build a production AI agent (from one API call up)A model API is a function from text to text — it remembers nothing, does nothing and fails without saying so. Everything an agent actually does lives in the program around it: the loop, the tools, the window, the budgets, the gates, the sandbox, the run log. Build that program, one mechanism at a time, until it can resolve a support ticket and issue a refund exactly once.
- AI Agent PlatformLong-running multi-step LLM agents — durable workflow + sandboxed execution + LLM gateway. Brain / hands / state are independently replaceable. The agent run is a workflow, not a request.
Browse the full problem catalog, or see what the simulator does and does not model.